This invention relates in general to laser targeting systems, and more particularly relates to a system and method for optical alignment of a color imaging system to a laser.
Multi-spectral sensor/laser systems are generally used to track and record targets and include laser-guided weapons systems and nighttime imaging/tracking systems. A common process used to align sensors in the multi-spectral sensor/laser system includes viewing a target through a boresight module at an image plane of a boresight collimator within the boresight module. The target is viewed simultaneously by all of the sensors to eliminate error in alignment that can occur when the target is viewed by different sensors at different times.
In the past, aligning multi-spectral sensors was accomplished by illuminating a target with a laser and viewing the target with the forward looking infrared (FLIR) sensor and a vidicon camera sensor that operates in the near infrared (NIR), i.e., 700 nm to 950 nm spectral region. Most multi-spectral sensor systems used a vidicon (or NIR) camera in conjunction with a color camera for the dual purpose of obtaining NIR spectral information and allowing boresight transfer to the color camera. An NIR camera can detect laser energy reflected off the target, while the FLIR sensor detects the infrared energy emitted by the heated target. But color cameras come with bandpass filters on the detector to obtain a photopic spectral response. The color cameras, therefore, cannot detect the reflected infrared energy. Without the NIR camera, the color CCD camera is unable to be passively aligned.
In accordance with one embodiment of the present invention, a method for optical alignment of a color imaging system includes illuminating a target plate with a laser beam. Photo-luminescent energy from the target plate is emitted in response to the laser beam. A color imaging system is aligned based on the photo-luminescent energy emitted at the target plate.
Technical advantages of one or more embodiments of the present invention include transmitting the laser energy to an absorptive second target plate directly behind a first target plate operable to emit photo-luminescent energy. Thus, after the laser fires a beam into the boresight module, the color CCD camera is aligned on the visible glow from the first target plate, while the FLIR sensor boresights on the second laser-heated target material behind the first target plate. Thus, these two independent sensors operating at different spectral regions may then be aligned simultaneously to establish a common line-of-sight.
Further advantages include allowing the use of one set of projecting optics to be used when boresighting the entire sensor suite instead of projecting a target from two different sets of optics. Therefore, the boresight errors that manifest themselves over temperature and other environmental perturbations are eliminated. Also, this invention eliminates the use of a NIR camera because the color CCD camera can view the photo-luminescent glow directly from the first target plate in the boresight target.
These and elsewhere described technical advantages may be present in some, none, or all of the embodiments of the present invention. In addition, other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, description, and claims.